Evaluation of HER2-specific peptide ligand for its employment as radiolabeled imaging probe.
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ABSTRACT:
SUBMITTER: Honarvar H
PROVIDER: S-EPMC5812989 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The interaction between the immune checkpoint PD-1 and PD-L1 promotes T-cell deactivation and cancer proliferation. Therefore, immune checkpoint inhibition therapy, which relies on prior assessment of the target, has been widely used for many cancers. As a non-invasive molecular imaging tool, radiotracers bring novel information on the in vivo expression of biomarkers (e. g., PD-L1), enabling a personalized treatment of patients. Our work aimed at the development of a PD-L1-specific, peptide-based PET radiotracer. We synthesized and evaluated a radiolabeled macrocyclic peptide adapted from a patent by Bristol Myers Squibb. Synthesis of [68 Ga]Ga-NJMP1 yielded a product with a radiochemical purity>95 % that was evaluated in vitro. However, experiments on CHO-K1 hPD-L1 cells showed very low cell binding and internalization rates of [68 Ga]Ga-NJMP1 in comparison to a control radiopeptide (WL12). Non-radioactive cellular assays using time-resolved fluorescence energy transfer confirmed the low affinity of the reported parent peptide and the DOTA-derivatives towards PD-L1. The results of our studies indicate that the macrocyclic peptide scaffold reported in the patent literature is not suitable for radiotracer development due to insufficient affinity towards PD-L1 and that C-terminal modifications of the macrocyclic peptide interfere with important ligand/receptor interactions.
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Project description:PurposeSystemic peripheral amyloidosis is a rare disease in which misfolded proteins deposit in various organs. We have previously developed I-124 labeled peptide p5 + 14 as a tracer for positron emission tomography imaging of amyloid in patients. In this report, we now document the labeling efficiency, bioactivity, and stability of Tc-99m labeled p5 + 14 for single-photon emission computed tomography (SPECT) imaging of amyloidosis, validated in a mouse model of systemic amyloidosis.ProceduresRadiochemical yield, purity, and biological activity of [(99m)Tc]p5 + 14 were documented by instant thin-layer chromatography (ITLC), SDS-PAGE and a quantitative amyloid fibril pulldown assay. The efficacy and stability were documented in serum amyloid protein A (AA) amyloid-bearing or wild-type (WT) control mice imaged with SPECT/X-ray computed tomography (CT) at two time points. The uptake and retention of [(99m)Tc]p5 + 14 in hepatosplenic amyloid was evaluated using region of interest (ROI) and tissue counting measurements.ResultsTc-99m p5 + 14 was produced with a radiochemical yield of 75 % with greater than 90 % purity and biological activity comparable to that of radioiodinated peptide. AA amyloid was visualized by SPECT/CT imaging with specific uptake seen in amyloid-laden organs at levels ∼5 folds higher than in healthy mice. ROI analyses of decay-corrected SPECT/CT images showed <20 % loss of radiolabel from the 1 to 4 h imaging time points. Biodistribution data confirmed the specificity of the probe accumulation by amyloid-laden organs as compared to non-diseased tissues.Conclusion[(99m)Tc]p5 + 14 is a specific and stable radiotracer for systemic amyloid in mice and may provide a convenient and inexpensive alternative to imaging of peripheral amyloidosis in patients.
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Project description:The prolonged in vivo persistence of antibodies results in high background and poor contrast during their use as molecular imaging agents for positron emission tomography (PET). We have recently described a class of engineered Fc fusion proteins that selectively deplete antigen-specific antibodies without affecting the levels of antibodies of other specificities. Here, we demonstrate that these Fc fusions (called Seldegs, for selective degradation) can be used to clear circulating, radiolabeled HER2-specific antibody during diagnostic imaging of HER2-positive tumors in mice. The analyses show that Seldegs have considerable promise for the reduction of whole-body exposure to radiolabel and improvement of contrast during PET.
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Project description:The high incidence and mortality of breast cancer supports efforts to develop innovative imaging probes to effectively diagnose, evaluate the extent of the tumor, and predict the efficacy of tumor treatments while concurrently and selectively delivering anticancer agents to the cancer tissue. In the present study we described the preparation of technetium-99m (99mTc)-labeled paclitaxel (PTX) and evaluated its feasibility as a radiotracer for breast tumors (4T1) in BALB/c mice. Thin Layer Chromatography (TLC) was used to determine the radiochemical purity and in vitro stability of 99mTc-PTX. PTX micelles showed a unimodal distribution with mean diameter of 13.46±0.06nm. High radiochemical purity (95.8±0.3%) and in vitro stability (over than 95%), up to 24h, were observed. Blood circulation time of 99mTc-PTX was determined in healthy BALB/c mice. 99mTc-PTX decays in a one-phase manner with a half-life of 464.3 minutes. Scintigraphic images and biodistribution were evaluated at 4, 8 and 24h after administration of 99mTc-PTX in 4T1 tumor-bearing mice. The data showed a significant uptake in the liver, spleen and kidneys, due to the importance of these routes for excretion. Moreover, high tumor uptake was achieved, indicated by high tumor-to-muscle ratios. These findings indicate the usefulness of 99mTc-PTX as a radiotracer to identify 4T1 tumor in animal models. In addition, 99mTc-PTX might be used to follow-up treatment protocols in research, being able to provide information about tumor progression after therapy.
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Project description:Background: Antibodies targeting surface expressed disialoganglioside GD2 are increasingly used in neuroblastoma immunotherapy and might also have potential for use in radioimmunotherapy. As such targeted treatments might benefit from a dedicated theranostic approach, we studied the influence of radiolabeling on the binding characteristics of ch14.18 antibodies produced by Chinese hamster ovary (CHO) cells and evaluated the benefit of GD2-ImmunoPET as a potential tool for therapy planning. Methods: 64Cu was used to reduce radiation burden, which is of high importance especially in a pediatric patient population. 64Cu-labeling was accomplished using the chelators NOTA- or DOTAGA-NCS. Radiolabeled antibodies were characterized in vitro. [64Cu]Cu-DOTAGA-ch14.18/CHO was studied in a neuroblastoma mouse model (subcutaneous CHP-134 xenografts). In vivo PET and MR images were acquired at 3 h, 24 h, and 48 h p.i. The specificity of binding was verified using GD2-negative tumors (HEK-293 xenografts), a control antibody and in vivo blocking. A first translational application was performed by PET/MRI in a patient with metastasized neuroblastoma. Results: Radiolabeling at an antibody-to-chelator ratio ≥1:10 yielded a product with a radiochemical purity of ≥90% and a specific activity of 0.2-1.0 MBq/µg. Radiochelation was stable over 48 h in PBS, mouse serum or EDTA, and 50.8 ± 3.5% and 50.8 ± 2.0% of the radiolabeled conjugates, prepared at antibody-to-chelator ratios of 1:10 or 1:15, were immunoreactive. In vivo, highly specific accumulation (31.6 ± 5.8% ID/g) in neuroblastoma was shown preclinically. Clinical PET/MR scans using [64Cu]Cu-NOTA-ch14.18/CHO (NOTA used for safety reasons) could visualize neuroblastoma metastases. Conclusions: In vivo, 64Cu-labeled ch14.18/CHO is suitable for specific identification of neuroblastoma in PET. A first patient PET indicated the feasibility of the method for clinical translation and the potential utility in image-guided therapy.
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Project description:PURPOSE:Copper-64 (Cu-64) and Galium-68 (Ga-68) radiolabeled DO3A and NODA conjugates of exendin-4 were used for preclinical imaging of pancreatic ? cells via targeting of glucagon-like peptide-1 receptor (GLP-1R). PROCEDURES:DO3A-VS- and NODA-VS-tagged Cys(40)exendin-4 (DO3A-VS-Cys(40)-exendin-4 and NODA-VS-Cys(40)-exendin-4, respectively) were labeled with Cu-64 and Ga-68 using standard techniques. Biodistribution and dynamic positron emission tomography (PET) were carried out in normal Sprague-Dawley (SD) rats. Ex vivo autoradiography imaging was conducted with freshly frozen pancreatic thin sections. RESULTS:DO3A-VS- and NODA-VS-Cys(40)-exendin-4 analogues were labeled with Cu-64 and Ga-68 to a specific activity of 518.7?±?3.7 Ci/mmol (19.19?±?0.14 TBq/mmol) and radiochemical yield above 98 %. Biodistribution data demonstrated pancreatic uptake of 0.11?±?0.02 %ID/g for [(64)Cu]DO3A-VS-, 0.14?±?0.02 %ID/g for [(64)Cu]NODA-VS-, 0.11?±?0.03 for [(68)Ga]DO3A-VS-, and 0.26?±?0.03 for [(68)Ga]NODA-VS-Cys(40)-exendin-4. Excess exendin-4 and exendin-(9-39)-amide displaced all four Cu-64 and Ga-68 labeled exendin-4 derivatives in blocking studies. CONCLUSIONS:[(64)Cu]/[(68)Ga]DO3A-VS-Cys(40)- and [(64)Cu]/[(68)Ga]NODA-VS-Cys(40)-exendin-4 can be used as PET imaging agents specific for GLP-1R expressed on ? cells. Here, we report the first evidence of pancreatic uptake visualized with exendin-4 derivative in a rat animal model via in vivo dynamic PET imaging.
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Project description:BackgroundHepatocellular carcinoma (HCC) is rising steadily in incidence, and more effective methods are needed for early cancer detection and image-guided surgery.MethodsWe used a structural model to optimize the peptide sequence. Specific binding was validated in vitro with knockdown, competition, and co-localization assays. Multi-modal imaging was performed to validate specific binding in vivo in orthotopically-implanted human xenograft tumors.ResultsBinding properties of WKGWSYLWTQQA were characterized by an apparent dissociation constant of kd = 43 nM, and an apparent association time constant of k = 0.26 min-1. The target-to-background ratio was significantly higher for the target versus control for both modalities. Ex-vivo evaluation using human HCC specimens supported the ability of the peptide to distinguish HCC from other liver pathologies.ConclusionsWe have identified a peptide specific for CD44 with properties that are promising for clinical translation to image HCC in vivo.
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Project description:Membrane type-1 matrix metalloproteinase (MT1-MMP or MMP-14) plays an important role in adverse cardiac remodelling. Here, we aimed to develop radiolabeled activatable cell penetrating peptides (ACPP) sensitive to MT1-MMP for the detection of elevated MT1-MMP levels in adverse cardiac remodelling. Three ACPP analogs were synthesized and the most potent ACPP analog was selected using MT1-MMP sensitivity and enzyme specificity assays. This ACPP, called ACPP-B, showed high sensitivity towards MT1-MMP, soluble MMP-2, and MT2-MMP, while limited sensitivity was measured for other members of the MMP family. In in vitro cell assays, radiolabeled ACPP-B showed efficient cellular uptake upon activation. A pilot in vivo study showed increased uptake of the radiolabeled probe in regions of infarcted myocardium compared to remote myocardium, warranting further in vivo evaluation.
| S-EPMC6332093 | biostudies-literature
Project description:PurposeTo evaluate the potential of anti-human epidermal growth factor receptor (HER)1- and anti-HER2-targeted radiolabeled antibodies and magnetic resonance (MR) imaging for imaging of orthotopic malignant pleural mesothelioma (MPM) in mouse models.Materials and methodsAnimal studies with 165 mice were performed in accordance with National Institutes of Health guidelines for the humane use of animals, and all procedures were approved by the institutional Animal Care and Use Committee. Flow cytometry studies were performed to evaluate HER1 and HER2 expression in NCI-H226 and MSTO-211H mesothelioma cells. Biodistribution and single photon emission computed tomography (SPECT)/computed tomography (CT) imaging studies were performed in mice (four or five per group, depending on tumor growth) bearing subcutaneous and orthotopic MPM tumors by using HER1- and HER2-targeted indium 111 ((111)In)- and iodine 125 ((125)I)-labeled panitumumab and trastuzumab, respectively. Longitudinal MR imaging over 5 weeks was performed in three mice bearing orthotopic tumors to monitor tumor growth and metastases. SPECT/CT/MR imaging studies were performed at the final time point in the orthotopic models (n = 3). The standard unpaired Student t test was used to compare groups.ResultsOrthotopic tumors and pleural effusions were clearly visualized at MR imaging 3 weeks after tumor cell inoculation. At 2 days after injection, the mean (111)In-panitumumab uptake of 29.6% injected dose (ID) per gram ± 2.2 (standard error of the mean) was significantly greater than the (111)In-trastuzumab uptake of 13.6% ID/g ± 1.0 and the (125)I-panitumumab uptake of 7.4% ID/g ± 1.2 (P = .0006 and P = .0001, respectively). MR imaging fusion with SPECT/CT provided more accurate information about (111)In-panitumumab localization in the tumor, as the tumor was poorly visualized at CT alone.ConclusionThis study demonstrates the utility of radiolabeled anti-HER1 antibodies in the imaging of MPM in preclinical models.Supplemental materialhttp://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12121021/-/DC1.
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